Unity always shows the FPS at 60 because of a feature called VSync, which sets the maximum FPS at 60. If you wish, VSync can be disabled by going to Edit > Project Settings > Quality and, in the "Other" section of the settings, set the 'V Sync Count' option to 'Don't Sync'.

The Quality section allows you to set settings for each of Unity's run-quality modes. So select each quality setting in turn and turn V Sync Count off in each one to ensure that it is always inactive.